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Blasting limescale off my pool walls - DONE & REPORT POSTED

My pool has limescale buildup all around the rim (waterline). In the past I paid somebody to bead-blast it off. This time around, it occurs to me that I can buy the equipment and do the job myself for the same $$$, and the blasting equipment will be there for future treatments and other uses. Can anyone give me any tips (type/size of glass beads to use, air pressure, likely bead usage rate, how to clean the beads out of the pool afterwards etc.) ? Oh, and my pool is mostly PebbleTec, but with some tiles. The scale is deposited on both surface types.

Re: Blasting limescale off my pool walls ?

Welcome to TFP!!

I suppose you could buy or rent the equipment (if you can find another use for it in the future) or just have someone else do it once more.

As you know you have, and will continue to have, this problem - why not treat it BEFORE it gets so bad you have to 'blast' it off? A minor change in your water balance might keep it down to a 'dull roar' and then you could manually take care of it with a bit of acid.

Check out JasonLion's calculator (in my sig) for where to 'optimally' park your chem numbers to reduce the occurence of the scaling Keeping the formation of the scale to a minimum via proper chemistry and tackling it early will prevent having to buy expensive blasting equipment and keep the blasted glass beads out of the pool

Luv& Luk
-Ted

Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

Re: Blasting limescale off my pool walls ?

Originally Posted by waste

Welcome to TFP!!

I suppose you could buy or rent the equipment (if you can find another use for it in the future) or just have someone else do it once more.

As you know you have, and will continue to have, this problem - why not treat it BEFORE it gets so bad you have to 'blast' it off? A minor change in your water balance might keep it down to a 'dull roar' and then you could manually take care of it with a bit of acid.

Check out JasonLion's calculator (in my sig) for where to 'optimally' park your chem numbers to reduce the occurence of the scaling Keeping the formation of the scale to a minimum via proper chemistry and tackling it early will prevent having to buy expensive blasting equipment and keep the blasted glass beads out of the pool

LOL - yeah, I know I should look after the pool chemistry better... I'm just too lazy ! Funny thing is I am a chemist by profession, specializing in analytical chemistry. I guess its kind of a busmans holiday for me

Re: Blasting limescale off my pool walls ?

OK, as nobody could give me any first-hand advice, I worked methodically through the problem. Firstly, here are some pictures of the pool BEFORE I got started:

My goal was to remove the limescale deposits by bead blasting without damaging my pool surface, and to do the whole project for under $300 (the minimum cost for having a professional do the job around here). Here is what I did:

Step 1) I went to Harbor Freight and bought the items shown in the pictures below. Total cost was $268 and change.

Yes, I know Harbor Freight stuff is made in China down to a price, but I've had good luck with their products in light-duty, infrequent-use applications, and it was about the only place I was going to get the required equipment within my budget.

Step 2) I used the submersible pump to drain the water from the pool. I placed the pump at the lowest point of the pool, next to the drain, and left it running overnight, pumping to the municipal drain at the front of my house via a regular garden hosepipe.

I got most, but not all the water out.

Step 3) I set up the blasting equipment per the sparse instructions, placed the glass beads in the hopper, set the compressor output regulator to 50psi, donned my protective goggles/gloves/facemask, and started blasting .

The pictures below show the work in progress, and clearly illustrate the difference between the blasted and unblasted regions. At 50psi, I saw no damage to the pool surface.

Step 4) After blasting the entire circumference of the pool, I used a household broom and dustpan to sweep up as much of the glass bead residue as I could, and dumped it into a bucket for later disposal. I then refilled the pool with fresh water and allowed the pool vac (Hayward Navigator) to remove the remaining glass beads (which have the appearance and feel of sugar sand).

The photos below show the pool after blasting - a considerable improvement !

The tiles are now totally scale-free, but the PebbleTec still has some discoloration. The scale was easy to remove from the cement surface, but much harder to remove entirely from the pebbles (not sure why). I was reluctant to be more aggressive for fear of damaging the surface. My recollection is that the professional that bead blasted my pool some years back had the same problem, and the surface was not perfect then either, so I am happy with this result.

This whole project took over my weekend. Would I do it again ? ABSOLUTELY !!! Its always more satisfying to do this kind of project, to learn from it, and to be self-sufficient in the future. However, with 20:20 hindsight I would make a few changes:

a) The submersible pump I chose was rated for 1400gph, so should have drained my 13,000 gal pool in about 9 hours - in fact, it took about 36 hours. I'm guessing this is because of the long distance the water was pumped through a 3/4" garden hosepipe to the drain. Next time I would get a pump with a higher flow rate, and a bigger hose .
b) The compressor I bought was inadequate. Although rated for 6gpm at 40psi (the blaster only needs 3.2gpm at 50psi), this compressor could not keep up at all. If I tried to blast continuously, the compressor overheated and cut out. In the end, I had to blast about 3 linear feet of pool wall, then wait about 5 minutes for the compressor to cool off. Either buy a bigger compressor, or rent one.
c) The 50lb bag of glass beads was not enough. I had to scoop up, clean and recycle some to complete the job. The recycled beads did not seem as effective. Next time I would just buy 100lbs of beads.
d) An N95 mask and goggles are not adequate protection. Those glass beads get EVERYWHERE. Some got inside my goggles, and I was even feeling grit between my teeth for a few days afterwards. Next time I would buy a cheap sand blasting hood.
e) If you are doing this in AZ, watch out for scorpions hiding under the pool rim. Bead blasting them only makes them angry .
f) The Hayward Navigator pool vac does not like glass beads. The beads are fine enough to get inside the rotor bearings and cause them to grind/jam. I limped through the cleanup, but next time I will be more diligent about removing the beads completely before using the pool vac.

I hope you guys find the story of my adventure interesting, informative and helpful. If you have any questions, let me know.

Re: Blasting limescale off my pool walls - DONE & REPORT POSTED

Originally Posted by StealthyBlagga

LOL - yeah, I know I should look after the pool chemistry better... I'm just too lazy ! Funny thing is I am a chemist by profession, specializing in analytical chemistry. I guess its kind of a busmans holiday for me

good post but, IMHO, it's less work and expense to keep the water balanced and keep the scale from forming in the first place than what you had to go through! Wouldn't you agree?

Re: Blasting limescale off my pool walls - DONE & REPORT POSTED

Originally Posted by waterbear

Originally Posted by StealthyBlagga

LOL - yeah, I know I should look after the pool chemistry better... I'm just too lazy ! Funny thing is I am a chemist by profession, specializing in analytical chemistry. I guess its kind of a busmans holiday for me

good post but, IMHO, it's less work and expense to keep the water balanced and keep the scale from forming in the first place than what you had to go through! Wouldn't you agree?

Yes, you are correct up to a point. Even with careful management and regular water changes, scale will still build up and require removal... even the most attentive owner is just delaying the inevitable IMHO. Remember, here in AZ our humidity is very low, and evaporative loss effectively empties my pool every year. The first few years I had this pool I was very diligent about managing the chemistry, but in the end the scale won out. At least now I can remove it anytime I like for minimal incremental cost. I do promise to be a good boy in future though

Re: Blasting limescale off my pool walls - DONE & REPORT POSTED

Granted AZ does have areas with very hard water but I would be interested in seeing your other wate quality parameters. High pH is one of the biggest predictors of scaling conditions and high TA can and will casue the pH to rise. If calcium levels are extremely hgh (say around 1000 ppm) then dropping the TA to around 60 and adding a secondary borate buffer system can be helpful to, at least, delay the inevetable.

Re: Blasting limescale off my pool walls - DONE & REPORT POSTED

Thanks for the great log of your tile blasting adventure. It just so happens I am in the midst of doing just the same thing, with almost identical equipment, bought at the same place, and having much the same results.

I have only done about 6 ft of my pool edge (3ft tile, 3ft Rock).

A couple of questions/comments for you and anyone else:

1) Qwestion: I am finding the #8 (MEDUIM: about 80 Grit) beads do a good job on the tile but have a harder time on the rocks or rough surfaces. QUESTION: would a larger bead, say #6 or about 60 grit work better on concrete and rocks?

2) Comment: the 80 grit at 50lb, with the cheap gun (I have the same one you used) still has a hard time with the limescale between the tiles (near on on the grout). I bumped it to 80 and then even 100 lb psi. I notices a slight haze on the tile when dry that I don't think I had at 50lb PSI. I will test this on a un-seen tile or two to check for sure.

2.1) Qwestion: On tile with small scratches from pumice stones and other efforts to remove the scale, what sort of sealant or tile polish do you think would give it a "wet look". The reason is, when the tile is wet it looke brand new. When dry it has a slight haze that appears to be from multiple tiny scraches to the glase surface.

I am going to try the 60 grit on the rocks and report back my findings.

Re: Blasting limescale off my pool walls - DONE & REPORT POS

I am about to give this a go. How can I get the glass beads out of the pool without messing anything up? Can I us one of those leaf vacuums that attach to the garden hose, can I just sweep them into the floor drain then clean the filters?

Noob Sue

23,000 vinyl wedge IG pool, built 2007
Hayward ProGrid Vertical DE3620 DE filter
Aquabot Robot
BBB since 2012
Hopkinton, NH, where we start swimming in lakes as soon as the snow is gone!